Agilent Increasing Productivity and Simplifying Sample Preparation With the SIPS Accessory Technical manual

Technical Overview

Increasing Productivity and
Simplifying Sample Preparation With
the SIPS Accessory

Flame Atomic Absorption Spectrometry (FAAS) typically involves element-specific
sample preparation which can be time consuming and prone to operator-introduced
errors. The SIPS 10 and SIPS 20 Sample Introduction Pump System (SIPS) are
optional accessories for Agilent’s SpectrAA FAAS instruments. They offer a range of
powerful features that automate many tedious and error prone sample preparation
tasks. These greatly simplify and speed up the sample preparation process,
improving productivity and reducing costs.

Combining a SIPS accessory with Agilent’s Fast Sequential capabilities results in an
easy to use, highly productive and cost effective atomic absorption solution.

Whether you are using an autosampler, or doing manual
sample introduction, a SIPS accessory, combined with the
SpectrAA software, will automatically:

– Prepare up to 10 calibration standards from a single bulk

standard, automating the instrument calibration process

– Intelligently dilute over range samples

– Prepare standard additions calibration from a single

standard

– Introduce analytical spikes, using a single standard

– Add chemical modifiers, e.g. ionization suppressants

– Extend the dynamic range of FAAS to that approaching

ICP-OES

The SIPS accessory is available in two versions:

– The single pump SIPS 10 provides in-line calibration and

sample dilution.

– The dual pump SIPS 20 has the additional capabilities of

in-line spiking of samples and in-line sample modification.

Figure 2. How the SIPS 10 works

How SIPS works

The sample flow rate of conventional peristaltic pumps
changes non-linearly with the pump speed. This makes
them unsuitable for use to automatically dilute samples.
The innovative design of the SIPS’ peristaltic pump system
ensures that the solution flow is proportional to the pump
speed, so the volume of solution being pumped is accurately
controlled. To extend the lifetime of the peristaltic pump
tubing (and thus lower operating costs), the SIPS will
automatically release the pressure on the pump tubing at the
end of run.

The SIPS 10 (Figure 1) combines a small flow of diluent with
the sample flowing to the nebulizer. If the pump speed is
reduced, the flow of sample is reduced. With a constant
nebulizer uptake rate, the diluent flow is thus increased
effectively diluting the sample. This simple approach makes
automatic calibration and in-line dilution possible, by accurately
controlling the pump speed with the SpectrAA software.

Figure 2. How the SIPS 20 works

2

The SIPS 20 comprises two pumps (Figure 2). One delivers
the sample and the second delivers a standard or modifier to
the nebulizer. Controlling the relative speeds of both pumps
allows the amount of standard or modifier added to the
sample to be precisely regulated. This allows in-line ‘spiking’
of samples.

No more tedious standard preparation

The SIPS 10 and 20 are capable of preparing calibration stan­dards from a single multi-element bulk standard. This reduces
sample preparation time and the risk of operator error during
standard preparation, which can lead to costly re-runs.

Using the concentration of the bulk standard, the SpectrAA
software can automatically determine standard concentrations
to cover the required concentration range.

Figure 3 shows an example of a calibration curve for Cu pre­pared from a single standard using the SIPS system. It has a
correlation coefficient of 1.0000, demonstrating the excellent
calibration accuracy that can be achieved with the SIPS.

The dilution accuracy of a SIPS is shown in Table1, demon­strating the ability of the SIPS system to provide accurate
results, even at high dilution factors. Figure 4 shows the dilu­tion performance of a SIPS with increasing dilution factors.
Excellent dilution accuracy was obtained across all dilution
factors with a maximum dilution error of just 1.2%.

Table 1. Typical dilution performance of a SIPS system, obtained by
repeating a number of standard measurements on different days under
different sequence conditions.

Dilution Factor 1 3-20 20-50 50-200

Standard Conc (mg/L) 5-10 10-100 100-320 200-1000

# of determinations 53 65 25 58

Dilution Error (%) -1 2 1 -1

Precision (%RSD) 1 1 1 3

Reproducibility (%) 1 1 2 2

Figure 3. Calibration curve for Cu prepared from a single standard, using
a SIPS. The concentrations of the standards were automatically set by the
SpectrAA software to cover the required concentration range.

Automatic in-line dilution

The dilution capability of a SIPS extends the working range
of AA by automatically diluting samples that are outside the
calibrated range. The SpectrAA software calculates the dilu­tion required to bring over range samples into the top half of
the calibrated range, where maximum precision and accuracy
usually occur. This ensures the integrity of results and eliminates
the need for costly re-analysis of samples at the end of a run.

Figure 4. Dilution performance of a SIPS 20 at different dilution factors.
Excellent dilution accuracy was obtained with a maximum of only 1.2%
dilution error.

Modifier addition

Flame AA methods routinely require the addition of chemical
modifiers for accurate results. These modifiers are normally
added during the sample preparation process. Using the
second pump of the SIPS 20, modifiers can be automatically
added during the analysis, taking a repetitive step out of the
sample preparation process. The amount of modifier added is
controlled by the pump speed, and this pump speed remains
constant during sample dilutions to ensure consistent blank
correction and matrix modification; something that must be
accounted for when adding modifiers manually.

3

In-line spiking of samples

The SIPS 20 automatically ‘spikes’ samples in-line, eliminating
sample preparation and reducing the risk of sample contami­nation. One pump introduces the sample, and the second
spikes the sample with standard.

In-line standard additions calibration

The dual pump SIPS 20 automatically adds addition stan­dards during the analysis. One pump introduces the sample
and the second introduces the standard. The SIPS system au­tomatically adjusts the speed of the second pump to achieve
the required additions—eliminating time-consuming sample
preparation and reducing the risk of contamination.

When maximum accuracy is required, the SIPS system en­sures that the calibration is completed using the linear portion
of the curve. Where necessary, the addition standards will be
diluted to ensure the absorbance signals fall within the linear
range.

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This information is subject to change without notice.

© Agilent Technologies, Inc. 2021
Printed in the USA, January 5, 2021
5991-6613EN